186SL0845171067701 246A 19850101 19921231 1758N 06703W 2 00000R 0000 MM 186SL0845271067701 Magueyes Island USA National Ocean Service 186SL084530001 186SL084530002 QUALITY ASSESSMENT OF SEA LEVEL DATA 186SL084530003 by the 186SL084530004 TOGA SEA LEVEL CENTER/NATIONAL OCEANOGRAPHIC DATA CENTER 186SL084530005 JOINT ARCHIVE FOR SEA LEVEL 186SL084530006 186SL084530007Station : Magueyes Island, P. Rico Latitude: 17 58.3N 186SL084530008Country : USA Longitude: 067 02.8W 186SL084530009JASL # : 246A Time Meridian: 060W (GMT - 4 hr) 186SL084530010GLOSS # : none TOGA #: none NODC #: 71067701 186SL084530011Contributor : National Ocean Service (NOS) 186SL084530012 National Ocean. and Atmos. Administration (NOAA) 186SL084530013 N/OES22 186SL084530014 SSMC4, STATION 7109 186SL084530015 1305 East West Highway 186SL084530016 Silver Spring, MD. 20910-3233 186SL084530017Originator : same 186SL084530018Original Data: Digital 186SL084530019Instrmnt Type: Analog-to-Digital Recorder (ADR) 186SL084530020Digitzd Intvl: 6 minute 186SL084530021Present Data : Hourly, daily, and monthly values obtained by: 186SL084530022 Hourly : Discrete sampling on the hour 186SL084530023 Daily : 119-point convolution filter (Bloomfield, 1976) 186SL084530024 centered on noon applied to the hourly data 186SL084530025 with respective periods of the 95, 50, and 5% 186SL084530026 amplitude points at 124.0, 60.2, and 40.2 hours 186SL084530027 Monthly: Simple average of all daily values; calculated if 186SL084530028 7 or fewer days are missing 186SL084530029Span of data : 01 Jan 1985 - 31 Dec 1992 186SL084530030Gaps > 1 mon : none 186SL084530031Time Refernce: GMT (hours 00-23) Space-filler Flag :-9999 186SL084530032Units : millimeters Missing Data Flag :99999 186SL084530033Refernce Levl: All heights have been referred to the station tide 186SL084530034 staff zero which is linked to fixed bench marks 186SL084530035Comment : The daily and monthly values do not show any 186SL084530036 obvious shifts or trends and agree well with San 186SL084530037 Juan. The monthly plot reveals a consistent 186SL084530038 annual signal. The sharp peak on 19 Sep 1989 is 186SL084530039 due to Hurricane Hugo. 186SL084530040 186SL084530041 CI MISSING REPLACED GAPS QUESTIONABLE 186SL084530042YEAR (%) DATA OR BAD DATA FLUCTUATIONS 186SL084530043---- --- -------------------- --------------- -------------------- 186SL0845300441985 99 none none none 186SL0845300451986 100 none none none 186SL0845300461987 100 none none none 186SL0845300471988 100 none none none 186SL0845300481989 100 none none none 186SL0845300491990 100 none none none 186SL0845300501991 100 none none none 186SL0845300511992 100 none (08)190-(01)191 none 186SL084530052 186SL084530053 QUALITY ASSESSMENT POLICY 186SL084530054 186SL084530055 The quality assessment is mostly based on the residuals 186SL084530056 (observed data minus predicted tides) of the hourly data. This 186SL084530057 assessment also applies to the daily and monthly data since 186SL084530058 they were derived from the quality-controlled hourly data. 186SL084530059 186SL084530060 The following abbreviations are used in the assessment: 186SL084530061 JASL - Joint Archive for Sea Level; GLOSS - Global Sea Level 186SL084530062 Observing System; TOGA - Tropical Ocean Global Atmosphere 186SL084530063 research program; NODC - National Oceanographic Data Center; 186SL084530064 Instrmnt - instrument; Digitzd Intvl - digitized interval; 186SL084530065 Gaps > 1 mon - missing data in a span greater than one month; 186SL084530066 Refernce - reference. 186SL084530067 186SL084530068 The following corrections are made to the hourly data 186SL084530069 prior to this assessment: 186SL084530070 1) Gaps or obviously wrong data points in a span less than 186SL084530071 25 hours are filled by the predicted tide method*. 186SL084530072 2) Timing errors of exact increments of an hour are corrected 186SL084530073 by shifting the data. 186SL084530074 3) Reference level shifts are only corrected after information 186SL084530075 from tide staff readings or comparative readings with a fixed 186SL084530076 bench mark are checked to verify that the shift was not a 186SL084530077 natural event. If comparative readings are missing or 186SL084530078 incomplete, comparisons of the data with nearby stations 186SL084530079 may warrant the adjustment of some obvious shifts. 186SL084530080 4) Data with unresolved datum shifts are not disseminated. 186SL084530081 However, if sufficient time spans of data are available before 186SL084530082 or after the year(s) with the unresolved shift(s), a subset of 186SL084530083 quality assured data is made available. Thus, the Span field 186SL084530084 in the Quality Assessment may not match the span of the 186SL084530085 distribution data set. As the questionable datum shifts are 186SL084530086 resolved, the data set will be updated. Although this policy 186SL084530087 adds some complexity, it allows more rapid dissemination of 186SL084530088 at least the quality assured years. 186SL084530089 186SL084530090 For each year, the following information is documented from 186SL084530091 the quality-controlled hourly data with dates given as the nth 186SL084530092 day of the year starting from 1 January: 186SL084530093 1) a Completeness Index (CI) based on the percentage of hours 186SL084530094 with available data, 186SL084530095 2) a list of gaps longer than a day, 186SL084530096 3) a summary of days with consecutive missing or obviously 186SL084530097 wrong data in a time span longer than 6 but less than 25 186SL084530098 hours that have been replaced, with hours in parentheses, and 186SL084530099 4) a summary of days with questionable fluctuations in the 186SL084530100 residual series. Fluctuations within the residuals are 186SL084530101 considered significant and are noted if they are greater than 186SL084530102 25 cm. This policy has changed slightly as of October 1992: 186SL084530103 only suspicious fluctuations due to obvious instrumentation 186SL084530104 problems are noted. Minor timing drifts are no longer 186SL084530105 included in the list of questionable days. 186SL084530106 186SL084530107 Note : If the predicted tides poorly model the observed heights 186SL084530108 due to the inability of the tidal analysis to completely resolv 186SL084530109 the non-linear shallow water effects, the residuals are not 186SL084530110 suitable for assessing the data quality. Instead, a subjective 186SL084530111 comment on the quality of the data is provided. 186SL084530112 186SL084530113 *The predicted tides are obtained with the use of a harmonic 186SL084530114 analysis program (Foreman, 1977) which is executed on a year 186SL084530115 of apparently good data for a given station. The Predicted 186SL084530116 Tide Method for filling gaps consists of statistically 186SL084530117 comparing the predicted tides to the observed data and 186SL084530118 shifting the predicted tides in time to correct for timing 186SL084530119 differences. Then the linear interpolation between hourly 186SL084530120 values at the end points of the gap in the residual series is 186SL084530121 added to the corresponding corrected predicted tide data to 186SL084530122 obtain interpolated values over the span of the gap. 186SL084530123 186SL084530124 Bloomfield, P., 1976. Fourier Analysis of Time Series: An 186SL084530125 Introduction. New York: John Wiley and Sons. pp 129-137. 186SL084530126 186SL084530127 Foreman, M., 1977. Manual For Tidal Height Analysis and 186SL084530128 Prediction. Institute of Ocean Sciences, Patricia Bay, 186SL084530129 Victoria B.C. Pacific Marine Science Report 77-10. 186SL084530130 186SL08456 19851 1131010 1135000 1172000 1182000 1183000 1172000 186SL08456 19852 1224000 1289000 1283000 1302000 1255000 1184000 186SL08456 19861 1159000 1130000 1139000 1197000 1180000 1187000 186SL08456 19862 1225000 1246000 1257000 1289000 1252000 1162000 186SL08456 19871 1128000 1169000 1168000 1123000 1127000 1162000 186SL08456 19872 1225000 1200000 1229000 1247000 1205000 1160000 186SL08456 19881 1161000 1146000 1094000 1120000 1119000 1137000 186SL08456 19882 1147000 1228000 1237000 1234000 1231000 1176000 186SL08456 19891 1117000 1100000 1093000 1126000 1142000 1151000 186SL08456 19892 1190000 1207000 1229000 1221000 1220000 1164000 186SL08456 19901 1174000 1126000 1101000 1131000 1131000 1140000 186SL08456 19902 1154000 1191000 1203000 1261000 1236000 1196000 186SL08456 19911 1158000 1141000 1136000 1118000 1175000 1213000 186SL08456 19912 1177000 1188000 1293000 1303000 1307000 1225000 186SL08456 19921 1177000 1161000 1176000 1182000 1168000 1183000 186SL08456 19922 1180000 1189000 1258000 1260000 1248000 1156000